Should I Accept that LinkedIn Invitation?

That’s a question I am almost guaranteed to hear during any social media workshop, or indeed, in one-on-one conversations about social networking. Even committed LinkedIn users are often uncertain of which connection requests to accept, or which invitations to extend: Someone who regularly shares your blog posts on Twitter? That guy on your condo board? Your cousin’s girlfriend with the commemorative-gold-coin business?

The problem of who to connect with on LinkedIn puzzles people precisely because the network itself is neither fish nor fowl. Is it a social network like Facebook, where your connections are (at least notionally) “friends”? A public platform like Twitter, where people can see and judge you on the number of your followers? Or just a really awesome address book?

It’s actually all of these things.

To use LinkedIn to its fullest potential, you need to tap its power as an introduction machine: an address book in which all the entries can see and connect with another, to create a mini-network with you and the things you share at the hub.

But that introduction machine only works if you are selective about which connections you initiate and accept.

I learned the value of selectivity the hard way. In the early days of LinkedIn, I connected with anyone who asked, just as I had on other social networks. But once I started trying to use it to get introduced to people I wanted to meet, I discovered that my promiscuity in making connections meant that most of my search results consisted of people I couldn’t actually get introduced to. Yes, each search turned up tons of potential connections — people who were connected to people I was connected with. But most of the time, that point of connection was someone I didn’t know well enough to ask for an introduction. I wasted hours digging through pages of search results just to find the two or three connections I could really leverage. You need a filter to help you connect to not just anyone you know, but only those people who will be able to help — or whom you can help yourself.

Thus was born the “favor test,” the answer to the who-should-I-connect-to-on-LinkedIn question.

The favor test is simple: Would you do a favor for this person, or ask a favor of them? If so, make the connection. If not, take a pass.

A favor isn’t constrained to an introduction; other kinds of requests come into play on LinkedIn: Would you support my charity? Will you attend my conference? Can you review my book?

When you’re thinking about whether to accept someone’s invitation to connect, imagine being faced with a request like this. (Note that there’s a difference between saying yes to a conference because it’s an interesting event, and saying yes because you want to help out the person who asked.) It’s the people you’d go out of your way to help or whom you trust to go out of their way to help you, however modestly, who pass the favor test.

If you’re consistent in applying the favor test, you can build a LinkedIn network that is useful and efficient in supporting any professional goal.

But you don’t want to be one of those people: the kind of person who evaluates people based on a number. The whole point of the favor test is to think about the two-way quality of your relationships. LinkedIn has its most dramatic impact when a favor goes from a hypothetical test to a tangible action — when you make those introductions, or when you meet that key individual at a company you’ve always dreamt of working for. Once you see your LinkedIn network not only as a way to realize your own goals but also as an asset you can share with the people you believe in, you’ll find it gives you much more than a few more sales leads, or a higher rank in the stack of resumes on a recruiter’s desk.

—For more on the favor test, and other ways to make the most of LinkedIn, check out Alexandra Samuel’s new e-bookWork Smarter with LinkedIn, just out from Harvard Business Review Press.